Method of making laminated metal blanks



Feb. 22, 1938. s. L. INGERSOLL 2,109,010

METHOD'OF MAKING LAMINATED METAL BLANKS Filed May 1e, 1935 Patented Feb. 22, 1938 UNITED STATES PATENT OFFICE METHOD OF MAKING LAM'INATED METAL BLANKS Stephen L. Ingersoll, Chicago, Ill., assignor to Borg-Warner Corporation, Chicago, Ill., a corporation of Illinois Application May 16, 1935, Serial No. 21,793

11 Claims. (Cl. 29-189) This invention has to do with the making of tobecompletely pervaded by or intermingled with composite metal blanks clad with a section of a constituents of the poured metal and thereby deselected metal, and relates particularly to an imprived of their special qualities. For example, proved welding process whereby the clad section when the envelope Walls are of stainless steel of a blank can be made extremely thin in comand the poured metal contains considerable carparison with the main body thereof. bon, the carbon transgresses the melted walls of Many uses are found for blanks comprising a the envelope and destroys their corrosion resistive surface section of special metal such as one havproperties. Such a limitation upon the coning particular qualities of hardness, toughness or temporary ingot process thwarts the making of a resistance to corrosion, or other chemical reacslab or sheet having a layer of the more expensive 10 tion. Such blanks are especially adapted for metal of a thickness less than approximately ffabrication into all kinds of metal Wear, tubs, teen per cent. of the total thickness of the finished tanks, barrels, vats and the like, whose contents article. The thinner the clad section of special are chemically active. When the composite metal with respect to the thickness of the whole 15 metal blank is made into a container, the special blank, the less expensive will be the blank. 15 metal surface may be exposed interiorly of the For many purposes a blank having a very thin Containel The main body of the blank and of clad section has a usefulness coextensive with or the elltanel' Wall may be 0f a leSS expensive greater than that of a blank clad with a thicker metal. Other instances are readily conceivable section or made entirely of the more expensive Where the use 0f en expensive metal iS required. metal. The advantage to be had from a process 20 but may be emplyed as effectively and with yielding a composite metal blank having a main greater economy in the form of a thin surface body or base of relatively inexpensive metal clad section upon a slab having a main body of a less with a thinner body than heretofore possible of a expensive metal. selected more expensive metal will be readily ap- A more advanced method presently employed parent. 25 for forming blanks having a main body of inex- The provision of such a process is the primary pensive metal such as mild steel and a clad secobject of the present invention. tion of more expensive metal such as stainless Another object of the present invention is the steel, includes the steps of forming an ingot by provision of an improved ingot process of making w casting a body of mild steel about an envelope metal blanks having laminations of different having opposed side Walls of stainless steel sepphysical characteristics and whereby the inarated by a weld-preventing material, rolling the gredients of a relatively thick lamination are ingot until the sections of the different steels are prevented from affecting the properties of a relaof a desired thickness,4 and thereafter trimming tively thinlamination.

the edges from the rolled ingot and dividing it The description hereinafter set forth of my 35 at a plane between the envelope side walls. Deimproved process will be fully understood when tails of the method thus summarized may be had read with reference to the accompanying single by reference to United States Patent No. 1,868,749, sheet of drawings hereby made a part of this issued to me July 26, 1932, for Process of makspecification, and wherein:

i9 ing laminated metal." Figure 1 is a cross sectional view taken through 40 'I'he presently known and applied ingot proan ingot mold and ingot therein formed in accesses of making laminated blanks are unadapted cordance with certain steps of the invention; and to making a laminated blank having an extremely Figure A2 is a fragmentary side elevation of a low ratio of special metal thickness to thickness blank made by the improved process.

gg of the body of base metal. It has been found Like reference numerals are used in the draw- 45 K that when the thickness of the walls of the ening and throughout the following descriptionof velope of special metal is less than substantially the invention. fteen per cent. of the combined thickness of 'Ihe process will be described as it may be'apsuch walls and of the ingot sections of metal 'cast plied to the making of blanks having a main body 5o thereto, the separating compound within the or base of ordinary iron or of steel and a clad 50 envelope becomes excessively heated and permits section of one of the so-called stainless steels portions of the opposed walls of the envelope to containing chromium and/or sometimes a small become welded together, thus frustrating the quantity of nickel. First, an envelope l0 is formed process. In some instances the envelope walls of a pair of similar. sheets Il of stainless steel.

5g becomeheated to the fluid stage permitting them Usually the sheets ll will be substantially rec- 55 tangular, although they may be any other conflguration. It is expedient to the process to use sheets II of dimensions approximating those of a vertical central section of a mold I2 so that when later the sheets are inserted into the mold all points upon their edges may be uniformly spaced from the walls of the mold. The envelopemay be sealed by welding-together the adjacent edges of the sheets or side walls II. The sealed joint between the side walls of the envelope I0 vis indicated by the reference character I3. The material forming the joint I3 is preferably identical with the material of the sheets II or one having closely allied physical properties. The joint I3 may be formed by spot welding. Such joint extends entirely about the peripheries of the opposed side walls I I.

A Enclosed within the envelope I 0 is a body of weld-preventing material I4. The function of the material I4 is to prevent the envelope walls II from becoming welded together during succeeding steps of the process. A compound of chromium trioxide (CIOs) has been found to serve effectively as a weld-preventing material. It is to be understood, however, that this compound is' mentioned but illustratively. Other weld-preventing materials may be used without departing from the scope of the invention.

The outer surfaces of side walls II of envelope III are thoroughly cleaned in any suitable manner as by pickling, and plates I5 of iron or steel placed against the cleaned sides thereof. 'I'he faces of plates I5 contiguous to the envelope are likewise cleaned. Plates I5 may be secured to the envelope III by joints I6, which may extend continuously about the edges of said plates. In addition to securing the plates I5 to the envelope I0, the joints I6, if continuous, serve to seal the plane-like interstice between the cleaned adjacent surfaces of the plates and the envelope. The joints I6 may be formed by welding adjacent sections of the plates I5 and of the envelope directly together, or additional metal may be used as a bonding element for the joint. If desired, the plates I5 may be otherwise supported Within the mold in close proximity to the envelope I0. Ordinarily it is more convenient to first assemble the envelope and the plates I5 into a unit and arrange them within the insert mold by a single operation.

'I'he unit assembled from the envelope I0 and plates I5 will be referred to as an insert and designated by the reference numeral I1. Because of the solid connections betweenthe component parts of the insert I'I, said insert may be easily handled for accurate arrangement within the mold I2. Usually the insert will occupy a central vertical plane of the mold in the manner illustrated in the drawing. Any means,A well known in the art, may be employed for supporting the insert within the mold. Various supporting means are -shown in my co-pending application Serial No. 712,893, filed February 26, 1934, for Method of making bimetal.

After theinsert I1 has been suitably placed within the mold I2, an ingot I8 is formed by pouring molten metal I9 into the mold and completely enveloping the insert I'I by the poured metal. The poured metal may or may not be of the same kind as the plates I5. It is at this stage of the process that the oce of the plates I5 is performed. The plates serve to absorb a portion of the heat of the molten metal, thus augmenting the heat absorbing effect of the wall sections II, and preventing complete melting Qf the Wall metal cast about the insert.

jected to friction in its subsequent use, the

poured metal will be of relatively high carbon content. In such case plates I5 containing little or no carbon will be selected so that they can absorb such carbon from the poured metal as tends to migrate to and intermix with the stainless steel parts I I. In this manner the stainless qualities of those parts are preserved.

As the process is presently employed the welding connection between the side walls of the envelope and the plates I5 are between the molten metal and the plates I5 is perfected incident to a subsequent rolling operation of the ingot, which operation is now to be described. Manifestly, however, if such quantity of metal is poured to adequately prolong its high temperature the weld between the molten metal andr the entire Iouter surface of the insert may be formed While in the mold.

After the ingot I8 has solidified, it is taken from the ingot mold I2 and passed between rolls (not shown) whose axis of rotation extends in substantial parallelism with the plane defined by the fiat envelope I 0. The ingot is hot-rolled until the sections of different kinds of metal therein are flattened to a desired thickness, .and have become thoroughly welded to one another over their adjacent surfaces. Thereafter, the rolled ingot which has become flattened and of increased area is trimmed about its edges, the trimming extending slightly into the envelope so that the iiattened ingot may be separated at the plane between the envelope side walls. II. The separating material I4 between side walls II permits of the ready separation of the ingot into two counterparts.

iron or steel and a comparatively thin section 22 of stainless steel; see Figure 2. That portion of main body 2I adjacent to the clad section 22 is composed of the material of a plate I5 WhileY the remainder of said main body is formed of the The dotted line in Figure 2 indicates the dividing plane at the juncture of metal originally in a plate I5 and poured metal.

The minimum thickness of metal plates I5 is determined both by the thickness of the envelope Walls I I and by the thickness of the body of molten metal. A molten body of predetermined dimensions will require an insert I'I having roughly the same thickness of solid metal between the interior of the envelope II) and the outer faces of plates I5. It follows that if the walls II of the envelope IIJ are comparatively thick, the plates I5 may be thinner and vice versa. If the dimensions of the molten body I8 are increased, an increase in thickness either of envelope walls II or plates I5, or both, will be necessary. Envelope walls of any gauge are possible to be combined into the ingot by simply using protective plates I5 of an adequate gauge'. Hence, it will be conceived that the ratio of special metal thickness Each counterpart constitutes a blank 20. comprising a main body 2I of the ordinary Reference herein to specific metals has been vmade to provide concrete exemplification of my new process; manifestly, other metals may be used according to the teachings of this specifica)- tion without departing from the fundamental principles underlying the invention.

What I claim as new and desire to secure by Letters Patent is:

l. The method of making laminated metal blanks, each having a thin surface lamination of a selected metal, comprising the herein described steps of forming a metal insert including a flat envelope having opposed side walls of such selected metal separated by a weld-preventing substance, and slabs o'f a diiTerent metal upon the side walls of said envelope and having their peripheral edges secured to said envelope, forming an ingot by pouring a body of molten metal about said insert, the thickness of a side wall of said envelope being less than, but the thickness of said insert at each side of said substance being at least equal to, the critical percentage of the perpendicular ldistance from said substance to the corresponding outer surface of said ingot, to prevent breakdown of said substance by the heat from the molten metal, flattening said ingot by hot rolling upon opposite surfaces. in substantial parallelism with the side walls of said envelope, and cutting into the body of said attened ingot preparatory to separating the same at the plane section between the side walls of said envelope.

2. The method of making laminated metal blanks, each having a main body of iron and a surface layer of stainless steel, comprising the herein described steps of forming a metal insert including a fiat envelope having opposed side walls of such stainless steel separated by a weldpreventing substance, and iron slabs upon the side walls of said envelope and having their peripheral edges welded to said envelope, forming an ingot by pouring a body of molten iron about said insert, the thickness of a side wall of said envelope being less than, but the thickness of said insert at each side of said substance being at least equal to, the critical percentage of the perpendicular distance from said substance to the corresponding outer surface of said ingot, to prevent breakdown of said substance by the heat from the molten metal, iiattening said ingot by hot rolling upon opposite surfaces -in substantial parallelism with the side walls of said envelope, cutting into the body of theattened ingot preparatory to separating the same at the plane section between the side walls of said envelope, and separating the ingot at such plane section.

3. The method of making laminated metal blanks, each having a surface section of stainless steel and a base portion of'. a relatively inexpensive steel, comprising the herein described steps of forming a metal insert including a flat envelope having opposed side walls of stainless steel separated by a weld-preventing substance and plates of such relatively inexpensive steel upon the side walls of said envelope and having their peripheral edges welded to said envelope, forming an ingot by pouring a body of molten steel about said insert, the thickness of a side wall of said envelope being less than, but the thickness of said insert at each side of said substance being at least equal to, the

criticalpercentage of the perpendicular distance from said substance to the corresponding outer surface of said ingot lto prevent breakdown of said substance by the heat from the molten metal, flattening said ingot by hot rolling upon opposite surfaces in substantial parallelism with the side walls of said envelope, cutting into the body of the flattened ingot preparatory to separating the same at the plane section between the side walls of said envelope, and separating the ingot at such plane section.

4. The method of making laminated metal blanks, comprising the steps of forming a metal insert including an envelope having opposed side walls of a selected metal separated by a weldpreventing substance, and a slab of a different metal joined to a side wall of said envelope, forming an ingot by pouring a body of molten metal about said insert, the thickness of the selected metal adjacent the slab being less than, but the thickness of said insert at each side of said substance being at least equal to, the critical percentage of the perpendicular distance between said substance and the corresponding outer surface of said ingot to prevent breakdown of said substance by the heat from said molten metal.

5. The method of making laminated metal blanks, comprising the steps of forming an envelope having opposed side walls of a selected metal separated by a weld-preventing substance, covering a side wall of said envelope with a metal plate, and forming aningot by pouring molten metal about the insert comprising said envelope and plate, the thickness of the selected metal adjacent the plate being less than, but the thickness of said insert at each side of said substance being at least equal to, the critical percentage of the perpendicular distance between said substance and the corresponding outer surface of said ingot to prevent breakdown of said substance by the heat from said molten metal.

6. The method of making laminated metal blanks, comprising the steps of arranging two plates of selected metal in opposed relation with a weld-preventing substance therebetween,y placing a plate of a different metal adjacent to and parallel with one ofvsaid opposed plates, forming an ingot by pouring molten metal about the insert comprising all of said plates, the thickness of the selected metal plate adjacent the plate of different metal being less than, but the thickness of said insert at each side of said substance being at least equal to, the critical percentage of the perpendicular distance between said substance and the corresponding outer surface of said ingot to prevent breakdown of said substance by the heat from said molten metal.

7. The method of making laminated metal blanks, comprising the steps of arranging two plates of stainless steel in opposed relation with a weld-preventing substance therebetween, covering one of the opposed plates with a heat absorbing metal plate adjacent to and in parallelism with the opposed plates, `forming an ingot by pouring a molten metal about the insert comprising all of said plates, and flattening said ingot upon a plane parallel with said plates, the thickness of the stainless plate covered by the heat absorbing plate being less than, but the thickness of said insert at each side of said substance being at least equal to, the critical percentage of the perpendicular distance between said substance and the corresponding outer surface of said ingot to prevent breakdown of said substance by the heat from said molten metal.

.8. The method of making laminated blanks from an ingot, comprising the steps of forming an envelope having opposed side walls of stainless steel separated by a weld-preventing substance adapted to break down from heat of molten metal when protected from the molten metal by solid metal of a thickness less than a critical percentage of the combined thickness of said solid and molten metals at each side of said substance covering one of said walls with a metal plate of low carbon content, and forming an ingot by pouring a body of molten metal of higher carbon content about the insert comprising said envelope and plate, the thickness of the wall covered by the plate of low carbon content being less than, but the thickness of said insert at each side of said substance being at least equal to, said critical percentage of the `perpendicular distance between said substance and the corresponding outer surface of the ingot.

9. The method of making laminated metal blanks, comprising the steps of forming an envelope having opposed side walls of stainless steel separated by a weld-preventing substance. placing adjacent one of said side walls a plate of metal substantially void of elements deleterious to the stainless steel side walls, and forming an ingot by pouring about the insert comprising said envelope and plate molten metal containing an element adapted to havel a. deleterious eect on the substance-engaging surface portion of said stainless'steel wall if united therewith, the thickness of the stainless Asteel wall adjacent the plate being `less than, but the thickness of the insert at each side of said substance being at least equal to, the critical percentage of the perpendicular distance between said substance and the correspending outer surface of the ingot to prevent breakdown of said substance by the heat from said molten metal.

10. A method of making laminated metal blanks, each having a relatively thin surface lamination Iof stainless steel not exceeding in thickness 15 per cent. of the combined thickness of the blank, comprising the stepsvof forming a iiat envelope from a pair of sheets of stainless steel whose juxtaposed faces are separated only by non-metallic weld-preventing material adapted to break down from the heat of molten metal when protected from the molten metal by solid metal of a thickness less than 15 per cent. of the combined thickness of the solid and molten metal on each side of said substance, covering the outer faces of said sheets with relatively thick iron slabs secured to the envelope so as to form therewith an insert, forming an ingot by pouring a body of molten metal, high in carbon content relative to the slab metal, about the insert to such an extent that the thickness of the insert at each side of said substance is at least equal to, but the thickness of each sheet is less than, substantially 15 per cent; of the perpendicular distance from said material to the corresponding outer face of the poured metal, flattening said ingot by hot rolling upon opposite surfaces in substantial parallelism with said envelope, and dividing the attened ingot at the plane section between the sheets of the envelope to provide a plurality of blanks. l Nail 11. The method of makingy laminated metal blanks, comprising the steps of forming an envelope having opposed side walls of a selected metal separated only by non-metallic weld-preventing material, shielding a side wall of said envelope with a metal plate, and forming an ingot by pouring molten metal about the insert comprising said envelope and plate, the thickness of a wall of said envelope being less than, but the lthickness of said insert at each side -of said material being at least equal to, the critical percentage of the perpendicular distance between Ysaid material and the corresponding outer surface of said ingot to prevent breakdown of said substance by the heat from the molten metal.

STEPHEN L. INGERSOLL. 

